Harry’s arrival will test William’s resolve. So will their father’s illness lead to a rapprochement between brothers?

It is not difficult to imagine the confusion of emotions that will flow through Prince William’s mind today: sadness and fear over his father’s illness, but also bewilderment at the enormity of the challenge he now faces and the inevitable sacrifices he will have to make.

The parallels with those his beloved grandmother faced more than seventy years ago are striking. The then Princess Elizabeth was 25 and a young mother when she unexpectedly succeeded her father as monarch.

She and Prince Philip had every reason to hope that they had more than a decade of family life ahead of them before the responsibility of the throne intervened.

William is sixteen years older than his grandmother at that crucial moment and his children are older, but his expectations for the future would have been no less.

And while he’s not about to become king, his life will change in every other way.

Suddenly, all of his and Kate’s meticulously thought-out plans, which prioritized the well-being of their children, now look fragile. What makes the uncertainty even greater is the brutal nature of the king’s condition.

Never has life in the royal family’s goldfish bowl felt so lonely or so dangerous. For William, the pressure is double as the additional burden that will come while his father undergoes treatment for cancer will have to be borne alone.

It’s only been eight days since Kate was released from hospital, where she underwent abdominal surgery, and it’s not expected she’ll be able to resume her public duties until after Easter. William himself has to go back to work tomorrow, after canceling all appointments to care for George, Charlotte and Louis.

It is not clear exactly how much of his father’s schedule goes to the prince. But the news that he will be going the extra mile comes with an additional distraction: Prince Harry’s decision to rush to his father’s side.

While it was unthinkable that Harry wouldn’t want to fly to Britain as soon as bulletins about Charles appeared, his presence will serve as a reminder of how fractured the royal family has become since Queen Elizabeth’s death in 2022.

It will be the first time he has seen his father since the coronation in May last year. Much to the relief of courtiers, the Duke of Sussex will apparently make the trip without his wife Meghan. The question is: will he see William too?

It is believed that the brothers did not exchange a word for months; their relationship apparently ended due to Harry’s memoir, Spare. In the book, published a year ago, Harry accused William of physically assaulting him and Kate of being cold towards Meghan.

As he struggles with his new responsibilities, William’s thoughts will almost certainly turn to how his grandmother would have handled such a princely incursion.

He may also draw some strength from the dignity with which the late queen met her fate all those decades ago. She obviously did this from a position of strength.

Public affection for her father, King George VI, for the way he guided the nation through the turmoil of the abdication and the dark days of World War II when she came to the throne in 1952. William comes to prominence with the monarchy in crisis.

It’s been less than two years since he and Kate made the adjustment in their lives that he hoped would pioneer a new royal lifestyle.

Their move from London to Windsor was not only about allowing all three of their children to go to school on the same day, but also about guaranteeing them a level of privacy that was never quite possible when they were based at Kensington Palace.

But the couple’s elevation to Prince and Princess of Wales has put a strain on this rural idyll. “They have a very nice life there at Adelaide Cottage in Windsor Great Park, but it does require a lot of moving parts to function properly,” says a friend.

Their staff is still based in London and meetings often have to take place at Windsor Castle.

The contrast between father and son as Princes of Wales could not be greater. Although Charles – like William – is passionate about what he believes in, he was also a lobbyist by nature. Not William. He has his core interests – homelessness, mental health and conservation – but doesn’t spread out like his father once did. For example, William has no interest in art.

But for now, at least, William will have to cover a lot more ground than he usually prefers. It is almost certain that he will take on his father’s role in receiving arriving and departing foreign diplomats.

So how will he deal with it? And more importantly, what does this change in status mean for his relationship with Harry?

Certainly, friends say, William has a knack for being dynamic, and some believe that taking on these additional responsibilities may have made him just that, raising both his profile and his visibility.

For starters, William enjoys one quality that his father had to wait years to acquire: public affection. From Princess Diana, William inherited a natural warmth and a confidence that is complemented by Kate’s dashing approach.

Even when they were accused of being “tone deaf” during their Caribbean tour to Belize, Jamaica and the Bahamas, criticism of the couple quickly dissipated.

Unlike Charles, who was aware of his future from an early age – he was heir to the throne at the age of three – William was protected from his fate for years.

“He really had no idea about it until he went to school,” says a former assistant. By the time he was at Eton, the Queen began teaching him the traditions and history of the monarchy over tea in Windsor.

Yet he postponed the inevitable as long as possible. After university and military service he became an RAF search and rescue pilot and later transferred to a civilian role in the air ambulance service.

It is in his approach to fatherhood that he differs so much from the king. While Charles has fit the arrival of his sons around his famously busy schedule, William has put family life first.

This is definitely the influence of Kate’s family. In the Middletons, William discovered how rewarding family life can be.

He will hope that his father’s recovery will eventually allow a partial return to those days of domestic bliss that many say will make him a modern and versatile sovereign.

However, there are two family issues that may determine this assessment: Andrew and Harry. As for Prince Andrew, he has strongly backed his father’s position that the Duke of York cannot return to frontline royal duties.

But as far as Harry is concerned, his opinion differs from that of the king. While Charles is torn by the conflict between his sons and longs for rapprochement, William is convinced that trust, the basis of any relationship, has been completely destroyed.

Harry’s arrival will test William’s resolve. Will he agree to see him, and in time agree to rapprochement, as his father surely wishes? Or will the status quo continue?

Charles’ illness and his recovery could determine that outcome.